Ultra low frequency ballistocardiograms (Bcg) and transcutaneous carotid artery pulse recordings (CP) are being made on patients of the Multiple Risk Factor Intervention Trial (MRFIT). Three clinical centers of MRFIT with 2000 patients and the Coordinating Center are involved in this ancillary study. Bcg a and CP are recorded on magnetic tape cassettes in standarized format controlled by a data encoder developed by the applicant. Cassettes are then mailed to the applicant's laboratory for analysis by digital computer. Analog recordings on the cassettes are converted to digital time series on industry compatable nine tract digital magnetic tape. This step is carried out on a specialized digital tape recorder. Data from these first pass digital tapes are then edited to produce second pass archive tapes with ideal properties for further processing. The editing procedure is accomplished on large scale computers of the main institutional computer center. Digital time series of Bcg and CP are then analyzed by a feature recognition and measurement (FRAM) program in the same machine. Standardized objective measurements of Bcg and CP obtained in this way are then employed in crossectional analyses and multivariate prognostic calculations. Bcg and CP are expected to demonstrate response to interventions and add important independent contributions to known predictive power of established risk factors for coronary heart disease.